By Andrew Anderson (@AndersonEvolve)
As an evolutionary biologist, it’s often a fun exercise to look at fictional creatures and think about how they might have evolved or how patterns in nature might apply to them. Ever since he became a playable in character in Mario Kart for SNES, I have always jumped at the chance to play as the King of the Koopas, Bowser–yes, even in Smash Bros where he’s a lower tier fighter. Video games aside, the lore around Koopas is sparse (or least from my knowledge), which leads to some great biological questions about how they function and survive. In particular, how do they reproduce and what mating systems might they have? In this post, I’ll set up some of the species boundaries of Koopas and in successive posts I’ll try to tackle some of the more interesting thought experiments.
First, we need to establish what creatures are Koopas. The classic concept of species is the Biological Species Concept, the idea that if populations can interbreed and yield fertile offspring, they are the same species (e.g. horses and donkeys can make a mule, but the mule is sterile–thus horse and donkey are separate species). This is a useful start point as it might help us demarcate what are and aren’t Koopas. In order to test the Biological Species Concept we need to know if interbreeding occurs. This is a dark-corners-of-the-internet thing, so I’ll just assume if a romance is present between characters then the result of a pairing would be fertile offspring. So a quick look at some known pedigrees in the Mario world and it looks like Koopas are pretty consistent in their appearance. Bowser had his 7 children for the early games (later retconned to be his minions, but some guide books still state they are his children), and one other child, Bowser Jr., who appeared in Mario Sunshine. We also have Koops who is the son of Koopley, and Kolorado who had an unnamed father in Paper Mario. Clearly Koopas beget Koopas.
But what about other denizens of the Mushroom Kingdom? Hammer Bros, Lakitus, and Boom Boom also have turtle-like appearances, so we’ll assume there isn’t any cryptic speciation (i.e., two different species that look similar) going on. It is also stated that Koopas evolved from Shellcreepers on the Mario Wikia. Shellcreepers still occasionally appear and certainly Bowser is as old as Shellcreepers, so they cannot be the ancestor to all Koopas. To be more accurate (although one can only do so much in a video game universe), I’m going to say Shellcreepers share a lineage with the other Koopas but are the most ancestral in form. Yoshis are from Dinosaur Land, which Bowser invaded, so they are geographically separate from Koopas. The only romantic entanglement we get from Yoshi is Birdo and neither are have the turtle-like appearance, so it seems unlikely Yoshi is a kind of Koopa. There is a strange thing to consider though; while not cannon, the Mario Bros live action movie suggests that most inhabitants are related despite their drastically different appearances (I would lose so much time nitpicking its evolution statements–so I’ll ignore them). It also shows Princess Daisy as being hatched from an egg–implying the human-like characters might be reptile-like as are the Koopas. We know Bowser is infatuated with Princess Peach, and his claim that Bowser Jr. was her son was believed, though not true. The fact that such a lie wasn’t immediately rejected suggests some plausibility. So it may be that the human-looking characters of the Mushroom Kingdom are also Koopas.
We can already see an issue with the Biological Species Concept. Are the princesses and Toads actually Koopas? What about Mario and Luigi? They’re from a different land and stated to be human, but have romantic interests in the two princesses. Clearly defining species is an interesting challenge in evolutionary biology. There are many ways to define a species in biology, though Biological is often a good start point for determining speciation in most sexually reproducing species. Scientists are uncovering more and more that hybridizations occur across lineages that are distinct enough to be considered separate species without sterilizing the offspring. In fact, humans have interbred with Neanderthals in the past despite the two being considered separate species. Evidence of this lies in sections of human genomes where parts of the sequence more closely match Neanderthal than the more ancient African lineage. Thus, those who can trace their ancestry to regions where Neanderthals co-occurred with humans have ~3-5% of their DNA inherited from Neanderthals. So even though it is hinted at the intermingling of the human-like members of Mushroom Kingdom and Koopas, it is still possible to consider them different species; therefore, given the drastically different morphologies and their reluctance to even cohabitate, I will treat the human-looking members of the Mushroom Kingdom as a separate species, but one capable of interbreeding with Koopas.
Now that we have determined what is and isn’t a Koopa, we can now move into the behaviors and morphologies that are found within the species. Stay tuned for the next sections of this blog which will discuss the mating system and brood-care strategies of Koopas…